Posts Tagged ‘david’

[Editor's note: This VisualBasic script from David Viljoen, Geological Survey of Canada, for ArcGIS solves a transparency flattening issue when trying to blend color into a grayscale shaded relief image. Often the colors become distorted during the merge. This tool preserves the color (hue) and moderates the saturation and value instead. I've used HSV color adjustment layers in Photoshop with relief masks to accomplish the same thing, nice to know it's available in ArcMap, too. Aileen mentioned it at NACIS Sacramento earlier this month.]

I developed the SatValMod (SVM) method to address the problems associated with traditional methods of integrating color with gray-scale raster data (e.g. layer transparency, multiplying color by gray-scale values, etc.).

The main problem with traditional methods is color loss or corruption. SVM does not change the original hue and modulates the saturation and value so that the final output has the same rich colors of your input data.

SVM does not require Spatial Analyst. It supports Grid, BIL, and TIF formats for input. It outputs a BIL file.

The SVM method involves a pixel-by-pixel transformation of RGB color coordinates to HSV space, modulation of the saturation and value color components, and transformation of the orginal hue and modulated saturation and value components back to RGB space. More details are available in the PowerPoint slide show included in the ZIP.

This technique can work with rasterized polygon layers. You will need to create a CLR file that relates pixel values to the polygon colors.

[Editor's note: IndieProjector lets users approach map projection as a Web 2.0 task. Anyone can upload data and reproject into a number of useful presets. This visualization shows the geographies popular with users, their data coverage. Most users are mapping the US and parts there of. But a few things stand out to me. Iran, a couple places in Africa, and the surprising number of people who think the world ends at the Rio de la Plata, Capetown, Melbourne, and Fairbanks. Are people using a cylindrical projection for their world maps, ahem, and it's just getting too tall for the page? None the less, a neat tool. Keep up the good work!]

After a few months of indieprojector, we thought it’d be interesting to see how it’s being used. Two questions sounded particularly fun to visualize: what geographic areas being mapped with indieprojector, and what projections are the most/least popular? So I grabbed some data and generated some maps, which Mark turned into snazzy visualizations.